Preparation of oil soluble petroleum sulfonates



1949 P. M. RUEDRICH PREPARATION OF OIL SOLUBLE PETROLEUM SUI-FONATES Filed May 28, 1946 F]: E 'L.

) AND QUANTITY or- ACID ADDED C -TOTAL OIL SOLUBLE. SULFONlC ACID RECOVER p m SULFON\C A" O\L SOLUBLE SULFONC ACID CONTENT PRODUCED BY CONVENTIONAL METHOD IO ADDED SULFONIC ACID- PERCENT BY WEIGHT FIIE E Acxo RECOVER? ssum or- (A) AND QUANTITY or- SULFONIC ACID ADDED.

10 ADDED SULFONIC ACID PERCENT BY WEIGHT INVENTOR. Pau/ M. Quear/ch ATTORNEY atented F eb. 22,. 1949 PREPARATION OF OIL SOLUBLE PETROLEUM SULFONATES Paul M. Ruedrich, Berkeley, Calif., assignor to Griffin Chemical Company, a corporation of California Application May 28, 1946, Serial No. 672,881

3 Claims. (Cl. 260-504) This invention relates to an improvement in the art of treating petroleum oils with strong sulfuric acid or with oleum to refine the oil without production of a so-called acid sludge and to produce, as a result of the treatment, a greater quantity of petroleum sulfonate.

It is usual in the production of various refined petroleum oils to treat the oil, as a step in the refining operation, with a relatively strong sulfuric acid or with oleum. When this is done, a three-phase system results, the components of which are (a) unreacted oil containing oil soluble petroleum sulfonates or mahogany acids, (1)) spent sulfuric acid and (c) an acid sludge. The proportional amount of sulfonic acids and acid sludge produced vary with type of oil used, the amount and the concentration of the sulfuric acid and the temperature at which the oil is treated. One conventional method of acid-treating the petroleum oils usually involves an acid application of very strong acid at a rate of about 30 lbs. per barrel of oil. This treatment usually results in the production of between about and 15% of the oil soluble sulfonic acids or mahogany acids.

The greatest portion of the sulfuric acid reacts with the unsaturated hydrocarbons present to sulfate these and form sulfuric acid esters; these are usually oluble in water and insoiuble in the mineral oil and are commonly referred to as "green acids. Upon aging the green acids undergo a transformation and eventually become water insoluble, probably due to the relative instability of the high molecular weight sulfuric acid esters which. upon hydrolysis, yield high molecular alcohols and free sulfuric acid. The liberated acid reacts with the alcohols and converts these into ethers. The sulfuric acid liberated upon hydrolysis also polymerizes the more unsaturated hydrocarbons and carbonizes a substantial portion of the polym e s so that the originally highly viscous acid sludge becomes a hard brittle mass which is insoluble in water and hydrocarbon oils.

The problem presented by the acid sludge produced from the sulfuric acid treatment of petroleum oils has long been a major disposal problem in the oil refining industry and the art is rich in suggestions and proposals as to how these can be treated to recover the hydrocarbon value and the acid values present. Although the problem has existed for years, only-three disposal methods are generally in use, (1) burning, (2) heating to destruction to liberate sulfur dioxide and form a coke residue and (3) waste storage. It should be obvious that a satisfactory acid refining operationwhich would reduce or eliminate acid sludge formation would be of material economic value.

The oil soluble sulfonic acids or mahogany acids" are widelyused in industry as rust preventatives, emulsifiers, detergents, petroleum additives and for many other uses. Heretofore, they have been derived as a by-product from the sulfuric acid refining of various petroleum fractions and their supply has been dependent upon the quantity of these produced from the refined oils manufactured. During World War II the requirements for petroleum sulfonates far exceeded the supply and, for a considerable period of time, the sulfonates were subject to strict allocation.

Attempts have been made to increase the quantity of sulfonates produced during refining, usually by increasing the quantity of oleum applied to effect a greater sulfonation of the petro leum. These attempts have not been successful; increasing the acid to oil ratio beyond an optimum ratio generally results only in an increased production of oil insoluble sulfonates and acid sludge Without any appreciable increase in the desirable oil soluble sulfonates content.

In accordance with the present invention, a process is provided which enables the quantity of oil soluble petroleum sulfonate to be materially increased at the same time that the formation of an oil insoluble-water soluble sulfonate and an acid sludge component are each either materially reduced or entirely eliminated. For example, utilizing the process of the present invention, it has been found possible to increase the production of desirable oil soluble petroleum sulfonates, utilizing the same petroleum oil fraction as a base stock, from between 5% and 15% by weight to between and by weight. I have found that if one adds to the oil, prior to the addition of the sulfuric acid or oleum added to effect sulfonation, a material which acts as an inhibitor of acid sludge formation, an increased yield of petroleum sulfonate can be effected and the formation of acid sludge reduced if not entirely eliminated. The material to be added must be relativeiy free from attack by the sulfuric acid or oleum added to effect sulfonation. In addition, the material added must prevent the oxidation and polymerization of the hydrocarbon contained in the oil fraction undergoing sulfonation into the acid sludge component. More particularly, I have found that if one adds to the oil prior to sulfonation, an oil soluble sulfonic acid, thereafter the oil can be treated with a strong sulfuric acid or oleum to refine the oil and produce an increased quantity of petroleum sulfonate in the oil with an almost entirely complete elimination of acid sludge formation. desired oil refining with an elimination of the acid sludge nuisance and waste and with a highly desirable increase in the quantity of petroleum sulfonates. v

For example, I have found that if one treats a-naphthenic type of lubricating oil, commonly marketed by the petroleum industry under the designation of 200 pale oil," under usual conditions of acid treating, the oil will form a very heavy acid sludge which is very diflicult to handle .yvhile only from to 12% of oil soluble sulfonates can be recovered; this holds true irrespective of the rate of acid addition and over relatively wide limits of acid strength. If to this same "200 pale oil." one adds, prior to the addition of the strong acid or oleum, between about 5% and 15% by weight of an oil soluble petroleum sulfonic acid and then treats the oil with the strong acid or oleum, acid sludge formation is absent or nearly so while the recovery of oil-soluble sulfonates will be increased to between 40%. and 50% by weight, depending upon the treatment temperature. .Taking into account the sulfonic acid originally added, the increase in total yield is from 10% to 36% by weight based upon'the original oil. The term concentrated acid used in the claim is intended to refer to the acids customarily used in this art and includes acids of from about 95% $03 to and including a fuming acid or oleum.

Thus one effects the acids and form sodium sulfate. The mixture was The quantity of sulfonic acid to be added to the oil prior to sulfonation can vary between 7 about 5% by weight and 15% by weight. I have generally obtained the best results with the addi- 3 tion of about 12% of the sulfonate on the weight of the oil. Below about 5% the effect of addition of the sulfonate is not appreciable, while above about 15% little added benefit is obtained, the

best result being generally obtained when about 12% by weight of the sulfonicacid is incorporated in the oil prior to sulfonation. The sulfonic acid used is preferably one previously derived by sulfonation of petroleum and which is oil soluble. One can employ any sulfonic acid, however, so long as it is oil soluble. If a sulfonate is added; the later acid addition converts the sulfonate into sulfonic acid and the corresponding sulfatef The base oils to which this invention may be applied include a wide variety of petroleum dis-1 tillates or refined oils. We have found a desirable stock to be one which has received initially a light treatment with 98% acid, sulfur dioxide or other solvent to remove a portion of the unsaturated hydrocarbons present and which do not, upon the practice of this invention, mate rially contribute to the increase in oil soluble sulfona'tes If these are not first formed and removed from the oil, an additional separation step may be necessary.

After the acid s lfonation in the presence of} the added sulfonic acid, the remaining oil is re-,

covered. It may be used as such. If its color is not satisfactory, the oil can be brightened or otherwise made acceptable color-wise by treat-. ment with clay or a suitable solvent as 98% 8111- furic acid, sulfur dioxide, furfural or other sol-,

vent, or by a combined treatment to give an oil of an acceptable quality. a

As illustrative of the practice'of the presenti invention and without limiting-the invention thereto, four batches of a 200v pale oil were weighed out (the oil having been first treated with 1 sodium sulfonate.

to provide the required quantity for batches 2, 3-

and 4, were placed in a lead-lined agitator provided with a water jacket. After completely solubilizing thesulfonic acid in the oil, 37.8 pounds of fuming sulfuric acid (20% S03) were added over a period of 45, minutes. Each mix- -ture was thorouhgly agitated and cooled during this period in order to below 80 the first batch but was absent from batches 2, 3 and 1. Following completion of the reaction, only sufiicient ,water was added to remove thefacid from the oil. A minimum quantity of water should be used, otherwise the water may pass into solution or form-an emulsion. With the oil treated, five gallons of water sufliced. These were slowly added to the mixture with agitation and cooling. The mixture was-settled for 24 hours with the formation and separation of two distinct layers The bottom layer was an aqueous solution containing the major portion of the spent sulfuric acid. The top layer was a homogeneous mixture of unreacted hydrocarbon oil, oil soluble sulfonic acid, oil insoluole sulfuric acid esters anccii a relatively small amount of spent sulfuric aci v An alternative method to effect a more rapid and complete separation of spend acid can also be used; It involves the dilution of the hydrolized acid treated oil with approximately an equal volume of a light petroleum hydrocarbon which can eventually be recovered for re-use by distillation. After withdrawing the spent acid the top layerwas neutralized with 13.4 pounds of a 50% solution of sodium hydroxide. The neutralized material was then diluted with twice its volume of isopropyl alcohol and the mixture settled for several hours. Three distinct layers were formed. The bottom layer was an aqueous slurry containing sodium sulfate and sodium salts of sulfuric acid esters. The middle layer consisted of hydrocarbon oil containing small amounts of sodium sulfonate and sodium salts of sulfuric acid esters in solution. The top layer was a, clear isopropanol solution of hydrocarbon oil and After decanting the top layer, the residue was treated with more isopropanol and the clear alcoholic extracts were combined and distilled. The residual material was a clear and highly viscous solution of sodium sulfonate in hydrocarbon oil. 7 a

The yield of the oil-soluble sodium sulfonate 'maintain its temperature produced in this new sulfonation process was F. The usual acid sludge formedwith tion. The results are shown in the following table:

Table {Batch 1 Batch 2 Batch 3 Batch 4 210 Pale Oil. pounds 75. 6 75.6 75. 6 75.6 Sulphuric Acid (2l% S03) pounds (50% by weight) 37.8 37.8 37. 8 37. 8 Bull'onlc Acid 100% basis) per cent of total weight 0.0 4. 8 8. 6 11.9 P ds 0. 0 4. 0 7. 9 11. 9 41.7 41.7 41.7 41.7 49. 3 64. 9 65. 4 66. 6 70.0 0.0 0.0 0.0 28.8 94.8 101.7 110.6 26.8 13.4 13.8 14.0 (10.. 29.1 108.2 117.6 124.6 Neutrahzed Acid Sludge from neutralization do. 96. 7 0. 0 0. 0 0. 0 Mineral Oil Recovered do 52. 7 55. 0 '7. 7 59. 4 Total sulionates recovered as sodium sulfonates. do. 29.3 33. 2 40. 4 48. 6 011 soluble sodium sulfonates recovered do. 9 9 20.3 31. 9 43. 6 Net Recovery of Oil Soluble sulfonates .do 0.0 16.7 25.4 34.0 Net Recovery of Oil Soluble sulionates "pi-r cent- 13.1 22. 1 32.9 45. 8

Comparing batches 2, 3 and 4 with batch 1, it will be observed that the formation and net recovery of sulfonates is increased by the prior addition of sulfonates, amounting respectively to 9.0%, 19.8% and 32.7%. As between batches 1 and 4, for example, nearly four times as much sulfonate was formed and recovered.

The operations reported above and in the table included an acid application at the rate of 50% by weight. Other operations were conducted in a similar manner but using the acid (20% $03) at the rate of 40% of the oil by weight. The results of both operations are shown graphically in the accompanying drawings wherein Figures 1 and 2 are respectively graphical representations of the per-cent. by weight of oil soluble sulfonic acid recovered upon the (1) addition of the indicated weight per-cent. of sulfonic acid and (2) treatment with 50% by weight of fuming sulfuric acid, in the case of Figure 1 and treatment with 40% by weight of fuming sulfuric acid, in the case of Figure 2. Referring to the drawings, increment A represents the sulfonic acid content produced by the acid treatment alone, a. constant value. Curve B represents the sum of the added sulfonic acid content and increment A, while curve C represents the total sulfonic acid content found as a result of the acid treatment The oil remaining was recovered in each case and given a light treatment with clay or 98% acid to improve its color to the extent desired. The oil was then of satisfactory quality.

The above description is not to be taken as limiting, but merely as illustrative of a mode of carrying out my process, but many variations may be made with respect to the mineral oil base employed in the sulfonation process. For instance, this novel method of sulfonating mineral oils may be used as effectively in the manufacture of transformer oil, spray' oil and medicinal oil.

I claim:

l. A process for producing oil soluble petroleum sulfonates from a petroleum oil comprising adding to the oil prior to sulfonation thereof between about 5% and about 15% on the weight of the oil of an oil soluble petroleum sulfonate, and adding concentrated sulfuric acid to the oil in the presence of the added petroleum sulfonate- 2. A process for producing oil soluble petroleum sulfonates from-a. petroleum oil comprising adding to the oil prior to sulfonation thereof about 12% on the weight of the oil of an oil soluble petroleum sulfonate, and adding concentrated sulfuric acid to the oil in the presence of the added petroleum sulfonate.

3. The process comprising treating a mineral oil with concentrated sulfuric acid in the presence of an oil soluble petroleum sulfonate dissolved in said fraction under sulfonating conditions, the sulfonate present in solution prior to sulfonation thereof being between about 5% and about 15% on the weight of the mineral oil.

PAUL M. RUEDRICH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1.477,829 Johansen Dec. 18, 1923 2,189,128 Breth et al Feb. 6, 1940 2,247,927 Smith July 1, 1941 2,416,397 Lemmon Feb. 25, 1947 OTHER REFERENCES LinhardLiebigs Annalen der Chemie, vol. 535, pp. 267-284, (1938). Copy-in Scientific Library. 

